In conventional RF signal chain designs, a low power analog base-band signal is generated based on a digital base-band signal. The analog base-band signal is modulated onto a RF carrier using a mixer or modulator, generating a low power RF signal. The low power RF signal is amplified and transmitted via an antenna. To achieve the required performance parameters such as signal to noise ratio, RF frequency range, and signal bandwidth, spurious free dynamic range high performance analog mixed signal components have to be used in these conventional systems.
Current steering digital to analog converters (DACs) are a popular architecture for generating analog RF signals from digital RF signals. High impedance current sources and fast switches, readily available in modern process technologies and using Kirchoff's current law for summing currents on a node are factors for the success of current steering DAC. However, for high output power applications, the current sources and the switching device consume a substantial amount of power during operation which makes current steering DAC not suitable for high output power applications.